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What Is a Refrigerant Scale? How Charging Scales Work

A refrigerant scale is a platform scale that weighs a refrigerant cylinder during a charge or a recovery. The technician places the cylinder on the scale, reads the starting weight, and then watches the weight fall as refrigerant moves into the system. Because the amount added is measured by weight rather than by pressure, the scale lets the technician add a known charge to a system. It is a simple idea, but it is one of the main ways to avoid undercharging or overcharging a system.

Quick answer

A refrigerant scale weighs the cylinder before and after a charge so you know how much refrigerant has moved. A standard electronic scale shows the weight as the charge runs, and you close the valve when the target is reached. A programmable scale takes a target weight and can close the valve on its own. Wireless scales send the readings to a phone or a manifold. Capacity, accuracy and resolution are the numbers that decide which scale fits the work.

How the weighing method works

The idea is to measure what leaves the cylinder. Yellow Jacket’s charging scale page describes the method directly: the refrigerant cylinder is weighed before and after charging. This avoids moving refrigerant from one tank into another to measure it, and it lets the technician charge the system directly from the cylinder. The same page says the scales can also be used to recover refrigerant from a system.

On a standard electronic scale, the display shows the weight of the cylinder while the charge flows. The technician watches the weight drop and closes the valve when the reading matches the planned amount. On a programmable scale, the technician enters the target weight in advance. Yellow Jacket states that the valve closes automatically when the charge is complete on its programmable models. The page also says the scales work with any refrigerant in any system, which means the scale measures weight and does not depend on the refrigerant type.

Types of refrigerant scales

There are three common types. A standard electronic scale shows the weight and leaves the valve control to the technician. A programmable scale adds a target weight and an automatic valve stop. A wireless scale sends readings over Bluetooth to a phone app or a compatible manifold, so the reading can be kept with the job record.

Yellow Jacket’s product line includes both standard and programmable scales in two capacities. Its standard electronic models are the 68802 at 110 lb (50 kg) and the 68812 at 220 lb (100 kg). The programmable models are the 68803 at 110 lb and the 68813 at 220 lb. Metric versions of the same capacities are listed on the same page. The wireless 68864 is a separate model with a 220 lb capacity and an app connection, described on its own page.

Fieldpiece’s scales page lists two HVAC/R models. The SRS1 is advertised with a 110 lb capacity and is described as a residential and light commercial scale. The SR47 is advertised with a 250 lb capacity and wireless operation. The body text of the page says the SR47 “weighs tanks up to 252 pounds” and includes built-in alarms to help during charging and recovery. These are the figures the page gives. A buyer should compare the cylinder size they actually handle with the rated capacity, because the scale is only as useful as the range it covers.

Capacity and accuracy

Capacity is the maximum weight the scale can hold. Yellow Jacket’s standard 110 lb scale is rated for 110 lb, and its 220 lb scale for 220 lb. Its page notes that the platform should not be loaded above the rated capacity, because that could damage the scale. A cylinder that is heavier than the scale’s capacity cannot be weighed on it, so check the full weight of the cylinder with refrigerant before choosing a model.

Accuracy is the number that decides how close the charge will be. For Yellow Jacket’s 110 lb standard scale, the page gives an accuracy of plus or minus 0.5 oz, or plus or minus 0.03 lb, or 0.1 percent of reading, whichever is greater. For the 220 lb scale, the page gives plus or minus 1.0 oz, or 0.06 lb, or 0.03 kg, or 0.1 percent of reading, whichever is greater. The programmable models add a charging accuracy figure: the page says charging accuracy equals the scale accuracy plus or minus 0.25 oz. The programmable 68803 and 68813 use that figure, which means a programmable scale can be more precise at the point of closing the valve than a standard scale is at the reading.

The wireless 68864 has its own accuracy statement. The Yellow Jacket page cites an accuracy of 0.05 percent and a resolution of 0.2 oz in the overview. The specifications section gives a reading resolution of 5 g. The page does not reconcile these two resolution figures, so a buyer who needs a specific resolution should confirm it in the manual before buying. We have not treated either figure as settled.

Wireless operation and records

A wireless scale adds record keeping to the weighing. Yellow Jacket’s 68864 page says it connects by Bluetooth Low Energy to its app for iPhone, iPad and Android devices. The page describes a display of weight, weight change and time since the last reset, and it says the readings can be saved to a smart device to keep a record of the service call. It also lists a 9 V battery included with the scale, rated for 40 or more hours, and an operating range of 32 to 122 F (0 to 50 C).

Fieldpiece’s SR47 is also described as wireless. A wireless scale is useful when the technician needs a record of how much refrigerant went into a system, or when the cylinder is on a cart away from the manifold. The record is only as good as the battery and the connection, so keep a spare battery and check the link before a charge starts.

Using a refrigerant scale safely

Set the scale on a firm, level surface before weighing. Do not load the platform above its rated capacity. Read the weight before opening the valve, and write it down. When charging, watch the cylinder weight and close the valve when the target is reached, or let a programmable scale do it. Recovery works the same way in reverse: the scale shows how much refrigerant has been removed.

Refrigerant is under pressure, and a cylinder that is handled roughly can be dangerous. Follow the cylinder’s own labeling, the manufacturer’s instructions, and local rules for handling and recovering refrigerant. A scale helps you measure the charge, but it does not replace the system’s charging data or a pressure and temperature check.

Scale or pressure-based charging

A scale and a pressure-based method answer different questions. A scale tells you how much refrigerant went into the system. Pressure and temperature readings, such as superheat or subcooling, tell you whether the system has the right charge for its current operating conditions. Many technicians use both: the scale for the amount, and the gauges or a superheat and subcooling check for the result. The Fieldpiece scale page describes the scale in terms of weight and alarms, not in terms of system charge targets.

What we could not verify

We could not open the Testo 560i product page. Its page returned a rate-limit error, so this guide does not use Testo figures for capacity, resolution, or intelligent-valve behavior.

We could not find an accuracy figure for Fieldpiece’s SRS1 or SR47 on the scales page we opened. The page says the scales are accurate but gives no number. Check the Fieldpiece manual for the exact accuracy of the model you plan to buy.

The resolution conflict on Yellow Jacket’s 68864 is unresolved in the sources we opened. Confirm it in the product manual before relying on a specific figure.

How we chose

We opened manufacturer product pages, manuals and knowledge base pages, and used only the figures and statements that appeared on them. Where two pages disagreed, or a figure was missing, we say so in the text. We did not use retailer listings, forums or third-party manual copies.

Sources

• https://yellowjacket.com/product/digital-electronic-charging-scales/
• https://yellowjacket.com/product/wireless-refrigerant-charging-scale/
• https://www.fieldpiece.com/product-category/scales/

Related guides

For the pressure and temperature side of charging, read our best clamp meter for HVAC guide. For a broader look at multimeters used in service work, see our best multimeter for home use guide.

Frequently asked questions

Is a refrigerant scale the same as a manifold gauge?

No. A manifold gauge reads pressure. A refrigerant scale reads weight. Many charges use both.

What size scale do I need?

Choose a scale whose rated capacity is above the full weight of the cylinder you use. Yellow Jacket lists 110 lb and 220 lb capacities. Fieldpiece lists a 110 lb SRS1 and a 250 lb SR47.

Does a scale work with every refrigerant?

Yellow Jacket’s page states that its scales work with any refrigerant in any system, because the scale measures weight. Check the manual for any model-specific notes.

Do I need a programmable scale?

Not always. A standard scale is enough when you watch the reading and close the valve yourself. A programmable scale is useful when you want the valve to stop at a target weight.